Hideya kobayashi

ABSTRACT

A LIGHTWEIGHT PRESTRESSED STRUCTURAL CONCRETE MEMBER COMPRISING A PLURALITY OF PRECAST RECTANGULAR CONCRETE BLOCKS ARRANGED IN SIDE-BY-SIDE RELATION, EACH OF SAID BLOCKS HAVING AT LEAST ONE ELONGATED RECESS ALONG AT LEAST ONE OF ITS PERIPHERAL EDGES SO AS TO FORM AN ELONGATED GAP BETWEEN TWO ADJACENT BLOCKS, SAID GAP BEING FILLED WITH CONCRETE MATERIAL AFTER STRETCHING WITHIN SAID GAP AT LEAST ONE WIRE OF HIGH TENSILE STRENGTH WITH A PREDETERMINED TENSION, WHEREBY THE BLOCKS AND THE CONCRETE MATERIAL FILLING SAID GAP ARE SUBJECTED TO PRE-COMPRESSION.

I2 Shouts-Sham l HIDEYA KOBAYASHI Llulllwlwlunx mms 'lmsslm STRUCTURAL.GLJNU1u-;'x1-: MEMBER AND Mlcllwn l-on MANUVAU'I'URINU 'Nm :mm1: L.,1968 Oct. 16, 1973 Orlglml [fi Imi Jam FIG. 5

OCL 16, 1973 HIDEYA KoBAYAsHl Re. 27,785

LIGHTWEIGHT PRES 'RESSED STRUCTURAL CONCRETE MEMBER AND METHOD FORMANUFACTURING THE SAME Original Filed Jan. 5. 1968 2 Sheets-Sheet 2 2e29 2a 22 U 33 33 United States Patent Office Re. 27,785 Reissued Oct.16, 1973 27,785l LIGHTWEIGHT PRESTRESSED STRUCTURAL CON- CRETE MEMBERAND METHOD FOR MANU- FACTURING THE SAME Hideya Kobayashi, 14-14, l-chomeNagaski, Toshima-ku, Tokyo, Japan Original No. 3,501,882, dated Mar. 24,1970, Ser. No. 695,967, Jan. 5, 1968. Application for reissue May 21,1971, Ser. No. 142,789

Claims priority, application Japan, Jan. 12, 1967, 42/ 1,952; May 9,1967, 42/ 28,886 Int. CI. E04h 2/10; E04c 3/10, 3/22 U.S. Cl. 52-228 5Claims Matter enclosed in heavy brackets l] appears inthe originalpatent but forms no part of this reissue specilication; matter printedin italics indicates the additions made hy reissue.

ABSTRACT F THE DISCLOSURE A lightweight prestressed structural concretemember comprising a plurality of precast rectangular concrete blocksarranged in side-by-side relation, each of said blocks having at leastone elongated recess along at least one of its peripheral edges so as toform an elongated gap between two adjacent blocks, said gap being filledwith concrete material after stretching within said gap at least onewire of high tensile strength with a predetermined tension, whereby theblocks and the concrete material filling said gap are subjected topre-compression.

BACKGROUND OF THE INVENTION The present invention relates to alightweight concrete member of a predetermined thickness 4for use as abeam or a slab for wall and/ or floor construction of a building, andmore particularly to a lightweight concrete member of such a type thatis constituted by a plurality of rectangular concrete blocks.

Hithertofore, in the art of manufacturing prestressed concrete members,two diiferent types of method have been known. These methods include the"pretension method and the post-tension method. According to the knownpretension" method, a concrete panel is moulded in a mould comprising arectangular framework having a plurality of tension wires stretchedunder a predetermined tension between the opposed side members of saidframework. As soon as the concrete panel is cured the framework isremoved from the panel leaving the tension wires therein. Thus, thewires serve to give a predetermined compression to the panel. By thismethod, a satisfactory prestressed concrete member can be obtained,however, this is disadvantageous in that an additional expense isrequired in providing the mould and that the mould cannot be removeduntil the panel is sufficiently cured.

The post-tension method is currently employed to an integrally mouldedconcrete member and it is not applicable to such a member that isconstituted by a plurality of concrete blocks.

SUMMARY OF THE INVENTION The present invention is directed to a novelprestressed concrete member and the method for manufacturing the samewhich is free from the above described disadvantages of the priormethods. It may be expressed that the present invention resides in itsnature between the pre-tension and the post-tension methods.

According to the present invention, a lightweight prestressed structuralconcrete member is provided, which member comprises a plurality ofprecast rectangular concrete blocks arranged in side-by-side relation,an elongated gap being `formed between each of two adjacent blocks alongthe edges thereof, said gap being tlled with concrete material, andmeans disposed in said gap for subjecting the blocks and the concretematerial in said gap to a predetermined pre-compression.

Further, according to the present invention, a method is provided formanufacturing the above described concrete member.

In order that the present invention may be more clearly understood andreadily carried into effect, reference may now be had to theaccompanying drawings in which several forms of the present inventionare illustrated by way of example, and in which:

FIG. l is a partially broken side view of a structural slab embodyingthe present invention;

IIG. 2 is a plan view of the structural slab shown in F l;

FIGS. 3, 4 and 5 show, in front, bottom and side views respectively, themanner in which tension force is applied to reinforcement wires in theslab;

FIGS. 6 and 7 are perspective views of a single precast block and amember constituted by nine of such blocks respectively;

FIG. 8 is a side view of a parallel-cord trussed beam; and

FIG. 9 is a perspective view of one block of said beam As abovementioned, generally the recessed blocks are rectangular, but they mayalso be square, and the drawing illustrates blocks of said square shape.

Referring now to the drawings, particularly to FIG. 6, the square block1 has a recess 2 in one of its surfaces side and the back side of therecessed portion is a plain flat surface.

The thin portion of the block at the back of the recess is extendedoutwardly from the sides of the square frames 3 of the blocks, and theperiphery 6 of the extended thin portion is also square and of a fixeddimension.

At the other periphery of the square frame 3, there are two projectedportions 4 in every four corners as shown in drawings, and the outsidesurface S of each projection 4 lies in the same plane as a peripheralsurface of the extended thin portion 6.

These precast concrete blocks 1 are reinforced with meshed wires orsteel bars, and also may be made of light- Weight concrete of lowwater-cement ratio by the aid of shaking apparatuses utilizing theinstantly releasing forms.

Such precast recessed blocks are assembled as shown in FIG. 7, with theouter surface 5 of the projections 4, and the peripheries 6 of theextended portions contacting each other precisely, there are obtainednarrow gaps 7, which are distributed rectangularly in latticed form.

Several high tensile strength wires 9 of fixed length are stretched ineach of gaps 7, and both ends of the wires 9 pass through holes in Tshaped anchor plates 8, which are situated at each end of the gaps. Thenenlarged heads are formed at both ends of the wires outside of theanchor plates by the aid of a heading machine utilizing high oilpressures.

Thus when the anchor plate 8 is drawn by jacks in outward direction,high tension is applied to wires 9 accordingly.

U shaped precast oblong blocks 10, each of which has the same length asone side of a recessed block 1, are arranged along the outer peripheriesof the assembly as shown in the drawings, and supporters 11 and jacksare situated outside of these oblong blocks 10 at every end positions ofthe gaps 7.

Steel bars 14 are attached to the anges 12 of the T shaped anchor plates8 with bolts and nuts 13, as shown in FIGS. 3, 4 and 5, and nuts 15 areinstalled to the other ends of the bars 14. A coupler 16 connectsanother steel bar 17 to each steel bar 14 as shown, and at the other endof the bar 17 an anchor plate 18 is attached, the two bars 14 and 17passing through the center holes of ramchairs (not shown) and that ofthe center hole rams 19, which are fed with oil under pressure frompumps.

When the high oil pressure of the jack-pump is fed to the centerholerams 19, the bars 14 and 17 are driven with strong forces in an outwarddirection, and high tension stress is applied to the wires 9.

At the time when the tension stress applied to the wires 9 issufficient, the nuts 15 are screwed tightly through the outer windows ofthe ramchair (not shown in drawings), then the couplers 16 areunscrewed, and the centerhole rams 19 and the bars 17 are released fromthe supporter 11, and fresh concrete is poured into the gaps 7.

In this case the compressive forces which result from the tensionapplied to the wires 9, are resisted through the supporters 11, theoblong blocks 10, the thin portions 2 and the projections 4 of therecessed block 1 which are distributed in latticed style in tworectangular directions as shown in the drawings.

When the strength of the poured concrete becomes sufficient incompression to resist the prestress of the wires, over a lapse of days,the bars 14 and the supporters 11 are released from the blocks, and thusthe constructive members of slabs for walls or floors are completed.

Referring now to FI-G. 9 a precast rectangular block 2l for parallelcord beams is illustrated in perspective view, and in this case adiagonal gap 27 for strength purposes is installed at the center of thecentral recess.

In the upper and lower sides of the block, an upper cord gap 22 and alower cord gap 23 extend through the entire width of the block inparallel relation as shown.

There are also thin portions 24 at the other side of the block, and thinguiding walls 34 project perpendicularly from the thin portion 24. Atthe right and left side of the block, vertical gaps 25 and 26 areformed, and triangle portions 28 are installed to strengthen the cornersof the guiding walls 34.

The recess is divided by the diagonal gap 27 into two parts 29.

When such a precast block 21 is arranged in a line as shown in FIG. 8,many high tensile strength wires 30 are stretched in the upper gap 22,and also in lower gap 23, and at the ends of these wires 9 they areattached to the T shaped anchoring plates 8 in the same manner as aboveexplained.

Then the compressive forces are resisted by the area indicated by thedotted line 32, when high tensile forces are applied to the high tensionwires 9 by the aid of the jacks (not shown), which are attached to theanges of T shaped anchor plates 8, also in the same manner as describedabove.

Some reinforcement of deformed bars are installed in the vertical gaps2S, 26, and diagonals 27, and fresh concrete 33 is poured in the gaps asshown in FIG. 8.

In such a manner, prestressed concrete beams with parallel cord trussescan be completed without any forms, and the cost of this fabrication isreduced remarkably.

Thus, lightweight structural concrete members, such as the parallel cordbeams and slabs for walls and oors, can be fabricated very economically,and buildings constructed from these structural members can be erectedwith remarkably low cost, because the members require minimum quantitiesof concrete without using any forms, and yet they have very highstructural efficiency.

The details of making such structural concrete members may be modifiedsubstantially without departing from the spirit of the presentinvention.

What is claimed is:

1. A structural assembly comprising a plurality of precast concreteblocks, each of said blocks having a pair of opposed surfaces andincluding a relatively thin peripheral CTI ange extending outwardlyalong the entire periphery at one of said surfaces and defining arectangular outline, said blocks being arranged so that the edges ofadjacent flanges of two adjacent blocks abut each other wherebyelongated recesses are formed between adjacent blocks, [at least oneoutwardly extending] projection [on] means at each side of [the] eachblock at the other of said surfaces of the blocks [block] and extendingbetween adjacent blocks for positioning such adjacent blocks such thatsaid projections having an edge surface which is in the same plane asthe edge of said ange whereby] when assembled the [end] edge surfaces oftwo adjacent blocks abut each other, wire reinforcement means disposedwithin said recesses and means engageable with said wire reinforcementmeans to apply tension force thereto, the latter said means beingpositioned to apply resistive compression force to said projection means[projections] during the application of the tension force to said wires,said recesses being filled with concrete, said projection meanscomprising at least one outwardly extending pro* ection at each side ofthe block having an edge surface in the same plane as the edge of saidflange.

2. An assembly as claimed in claim 1 comprising anchors in each recessengaging the wire reinforcement means at the ends thereof, said meansfor applying the tension force to the wires being detachably engageablewith said anchors.

3. An assembly as claimed in claim 1 wherein said recesses extend in twoarrays, one array at right angles [angle] to the other.

4. An assembly as claimed in claim 1 wherein said means for applyingtension force to the wire reinforcement means comprises a support memberadapted to contact the assembly and engage the wire means so that whenthe latter is subjected to tension, the assembly is subjected tocompression through application of force through said projection means[projections] [5. An assembly as claimed in claim 1 wherein twoprojections are provided extending at right angles to one another ateach of the corners at said other surface of each block] 6. An assemblyas claimed in claim 1 wherein two of said projections are providedextending at right angles to one another at each of the comers of eachblock at said other surface thereof.

References Cited The following references, cited by the Examiner, are ofrecord in the patented `tile of this patent or the original patent.

UNITED STATES PATENTS 517,576 3/1894 Lee 52-227 1,028,578 6/1912 Lund52-227 1,214,442 1/ 1917 Edlin 52-227 FOREIGN PATENTS 116,346 6/1918Great Britain.

618,431 2/ 1949 Great Britain 52-436 682,619 5/ 1951 Great Britain52-228 709,678 6/ 1954 Great Britain 52-227 713,211 11/ 1941 Germany52-228 835,798 4/ 1952 Germany 52--228 212,826 3/ 1941 Switzerland52-228 FRANK L. ABBOTT, Primary Examiner J'. L. RIDGILL, In., AssistantExaminer U.S. Cl. X.R. 52--438, 602

